


United Kingdom of Smash!

by Mechabees



Category: Harry Potter - J. K. Rowling, 僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia
Genre: Crack Crossover, Crossover, Gen
Language: English
Status: In-Progress
Published: 2018-09-25
Updated: 2018-09-24
Packaged: 2019-07-17 07:52:48
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 3,169
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16091276
Author URL: https://archiveofourown.org/users/Mechabees/pseuds/Mechabees
Summary: All Might and Harry Potter are two heroes. What would happen if the normally shy Harry was just like All Might in more ways than one. This is his story.





	1. Go Beyond!

Yagi Toshinori, better known as the Number One Pro Hero All Might, did not die in saving lives from the latest disaster of the week as most would assume, but rather in his sleep one night at age 69. He passed knowing his protege Izuku Midoriya had succeeded him as the symbol of peace and the world was in safe hands. While the memorial for All Might had thousands of attendees, the funeral for Yagi Toshinori was much more modest in size. The only thing of note at the funeral as far as the public was concerned is that the number one pro hero Deku would be speaking at it. At one point, through the tears, Deku said to the crowd “Toshinori once told me ‘meddling when you don’t need to is the essence of being a hero’, so I’m sure even now Toshinori is still meddling.” Deku had no idea how true his words were.

In a different time and place a baby with emerald green eyes and a heavy destiny to bear was born.


	2. Get Ready Ya Bunch of Newbies

Destiny, Fate, and Reincarnation are forces of nature that are incomprehensible in their design. Adding magic to the mix was like adding firecrackers to a delicate chemical procedure. Then adding the unique quirk One for All to the mix was like taking the that room of fire and chemicals and placing it in a supernova just to see what would happen. While All Might no longer held the active form of One for All he had transferred to Izuku, the quirk still left an indefinable mark on his soul despite lacking the “spark” that powered the quirk in its active user. Needless to say when his soul was ready for reincarnation the process did not quite go according to plan.

 

Typically the soul would retain no memories of their past life and would be a clean slate for their new life. All Might’s life had never been so simple so why should his death? The unstable cocktail of forces that surrounded All Might and the soon to be born Harry Potter ended up clashing spectacularly while his soul slipped through the cracks without being “wiped clean” as it were. When this incident was discovered several centuries later the forces that run the universe were terribly embarrassed.

 

_The one with the power to vanquish the Dark Lord approaches..._

 

All Might was terribly confused. Typically when faced with confusion he would laugh and deflect the question with his boisterous personality. When he lost access to his muscular form he had learned to cough up some blood on command and that would usually derail the uncomfortable conversation pretty quickly. All Might attempted to shake his head to refocus on why he was confused. Key word being attempt. All Might felt his heart sink in horror when he realized he could not move his head and to top it off he could only see indistinct blurry shapes. He could hear indistinct voices that sounded like he was underwater. Trapped, confused, and rendered senseless All Might, former number one pro hero, gave into his new bodies instincts and cried.

 

James Potter was a Mess, emphasis on the capital M. The day had started out easy enough, he woke up with the love of his life Lily. Lily had then gone over the birth plan for the 6th time this week. “Don’t worry Lily I got it, I get you settled, floo Madam Pomfrey and bring her back to you, and then stand in the corner and wait for further instructions with a cold towel.” he told her while rolling his eyes.

“I know James I just know that when it all happens you’ll inevitably get excited, and when you get excited things tend to go wrong spectacularly.” she replied.

“Name one ti-”

“Sixth year, I agreed to go on a date and you accidentally flooded the bottom two floors of the castle.” Lily interjected.

“That was an accident and nearly mostly Sirius’s fault!” James replied with a sheepish look on his face.

“It took them four days to clean up the mess James! Four days! The Slytherins and Hufflepuffs slept on makeshift rafts, and don’t get me started on the time you snuck three zebras into Astronomy, honestly how you got three of them to a castle in Scotland I never want to know.” Lily ranted.

“Well don’t worry this time Lily I promise with 100 percent certainty that nothing will go wrong with the birth!” James stated confidently as if begging the universe to prove him wrong, which of course it proceeded to do.

 

It all started, as it typically did, with Sirius showing up. “Prongs is my godbaby here yet!?” Sirius shouted barely a second after bursting through the door. The universe, realizing Sirius Black was in the top 5 people you don’t want in the room when giving birth, right behind Voldemort and his top Death Eaters, decided now was the perfect time for Lily to start giving birth. Sirius “No-Good-Rotten-Man-Whore-Damn-That-Smirk” Black upon hearing Lily’s pronouncement proceeded to let loose a high pitched scream and start babbling about baby-proofing the house while transfiguring every hard piece of furniture in sight into bean bag chairs.  
James had been traumatized by Lily enough over the past few weeks into remembering his “Baby Birth To-Do List” that he jumped into action sitting Lily on their ex-coffee table now bean bag chair before rushing to the fireplace and grabbing a pinch of floo powder.

“Hogwarts, Hospital Wing!” James shouted over Sirius’s incoherent screeching in the background. Sticking his head in the flames James shouted

“Madam Pomfrey!!”

James could see the door to the hospital wing open, but rather than Madam Pomfrey entering it was instead Minerva McGonagall looking incredibly alarmed.

“James what’s the matter?”

“The baby is coming and we need Madam Pomfrey quick.” James replied.

“There was another attack in Hogsmeade and she went to attend to the wounded, step aside I’m coming through. Merlin knows Lily is doomed if she only has you for support.” McGonagall tersely stated.

“Sirius is here too” James mumbled as he removed his head from the fireplace and mentally geared himself to putting up with the force that is his former Transfiguration professor.

McGonagall stepped through the fireplace and quickly took in the scene. James was in the corner holding a towel looking incredibly confused now that he was at the end of the list he had engraved into his brain. The living room was filled with what looked like large cushions and she could hear what sounded like Sirius Black down the hall accompanied by the crack and sizzle of magic spells being fired. Lily was on one of the cushions at the center of the room with a look that was a cross between severe pain and severe anger.

“Sirius Black you quit your nonsense this instant” McGonagall said using her best ‘scare students straight’ voice. The screeching died off in the other room and Sirius reentered the living room looking like a dog with his tail between his legs. Under McGonagall’s swift direction the birth proceeded at a much smoother pace, even if it was a bit awkward to have one of your old professor’s take part in the birth of your child/godchild. Madam Pomfrey showed up several hours later and just before midnight on July 31st Harry James Potter was born.

 

_...born as the seventh month dies…_

 

Lily Potter did not think she would see anything more beautiful and precious than her son. He had her eyes and she could already spot tiny tufts of black hair on his head. And wow did he have a set of lungs on him. Lily looked down as Harry started crying. James and Sirius headed over from their conversation with Madam Pomfrey at the sound, but everyone in the room stopped as they felt a ripple of magic come from young Harry. James and Sirius’s face lit up as they started shouting

“Barely an hour old and he’s already had his first bought of accidental magic!”

Lily looked at her baby with a soft smile on her face and whispered quietly to herself

“He’s going to be something special.”

 

Magic was a strange as far as fundamental forces of the universe went. It was ever changing, constantly ebbing and flowing creating wonders and horrors beyond belief in equal measure. Magic did not obey any forces of the universe with any type of consistency and the greatest minds of the magical world over the years still found themselves scratching their heads in confusion the more they tried to understand. Albus Dumbledore one of the greatest magical minds of the current era was a notoriously serious academic early in his career. However, the deeper he studied magic the more he realized that it was a force that even if you could understand it one day may very well change the rules it played by the next as a giant middle finger to the world. After coming to this realization Dumbledore’s mastery of magic grew by leaps and bounds although he did start wearing crazy multi colored robes and grew increasingly eccentric. The most people were able to determine about the true nature of magic was that it was inextricably related to the soul in some unknown way.

Conversely, quirks while extraordinary in their capabilities were much easier to understand as representations and extensions of the souls who possessed quirks. They were highly specific to the individual except in the case of One for All. One for All was an anomaly. Quirks did not combine, they may have several aspects to their power range and use, but they did not combine except in One for All’s case. At face value One for All was a transferable stockpile quirk with generations of power built up in it. Yet it did not have a finite reservoir of power that could be used up and have to rebuilt again. One for All was quite a bit more complicated than that. With each person who “cultivated” the power they gave a bit of themselves to the quirk. The quirk then used these essences to produce the power it granted its user. The more users who had time to actually cultivate the power then the more essences to provide power production, thus the increase in strength by subsequent users. This machinery of essences was useless without the pilot light to keep it going that is the quirk. So while the structure remained behind in All Might after he gave up the power,  he only had the remaining fumes the quirk had left behind to power it.

Magic and quirks were never supposed to coexist.

Yet when All Might’s soul was reborn in young Harry Potter without being wiped clean, the remnants of his quirk came along for the ride. The newly burgeoning magic in this new body had no mind of its own. What it could do was respond to the soul and will of its user. All Might’s soul had grown used to One for All over his years of use. It was a small leap for this new magic to provide the jumpstart that his quirk needed.

The process was not pleasant, as two forces that were not supposed to coexist stretched at the very fabric of the newly dubbed Harry Potter’s soul to make room to accommodate one another. The pain was so great the majority memories that were the previous life of All Might pushed down in an attempt to alleviate the pain.

Lily and James would call Madam Pomfrey several times that week since Harry just would not stop crying. She was unable to detect what was causing him so much pain. His previous life’s memories would not resurface for over a year.

The trauma of being hit by the killing curse and following explosion was just the trigger needed to start the reintegration of All Might’s memories.

 

Petunia Dursley was perfectly normal thank you very much with her normal husband and normal darling son. This was all shattered when she woke up to her nephew on her doorstep one morning. Her nephew was NOT normal, no matter what he said.

“I AM HERE, AND COMING THROUGH THE DOOR LIKE A NORMAL PERSON!”

Petunia looked up from her afternoon tea with a scowl on her face.

“Be quiet boy or the neighbors will hear you” she shrieked.

Coming through the entryway to the kitchen was her nephew. At age 6 Harry Potter was an even 6 feet tall and she hated how unnatural it was. She hated the smile that was always on her nephew’s face no matter how many chores she gave him. He would just laugh at the list and state “A hero’s work is never done!” and get the work done while loudly shouting about how great the training was. The nerve of him!

She and Vernon had such a hard time explaining why their nephew had the build of an adult bodybuilder with at the tender age of five. Vernon was always making excuses about an overactive gland when the neighbors questioned them about it.

“Young Aunt Petunia, I have finished with your list are there any other services you require from this hero!?” her nephew boomed.

“No, be quiet you insufferable brat and go to your cupboard.” She snarled.

The cupboard at Number Four Privet Drive had received some alterations over the four years of housing their nephew. The two major ones were the two holes in the wall adjacent to the cupboard her nephew’s feet would stick out of.

Harry gave a sigh as he wedged himself into his cupboard, the ever present smile slipping off his face now that he was alone. Honestly if it weren’t for the memories of his life as All Might he doesn’t know how he would have survived living in this house. Even if he could only start recounting the memories clearly starting six months ago, the heroic instincts had always been present as far as he could remember. His pre school days had been filled with loud boisterous laughs and relatively heroic deeds for someone so young. It had started innocently enough when he rescued one of Mrs. Figg’s cat, Mittens or something, but things had only snowballed out of control from there.

 

Harry was walking home from school because his aunt said she didn’t want to waste the fuel to pick him up. He thought this was rather odd reasoning since she picked up Dudley at the same school anyway but he didn’t mind. Harry’s head shot up as he heard someone cry out.

“Help! Someone stop him please, he has my son!”

Looking across the street Harry saw a woman chasing after a masked man who was carrying a child. Before he could think any further Harry was running.

By the time Harry had crossed the street the man had entered a car the passenger side of a car that was running with a driver in it. As the car started to take off with a squeal of the tires Harry did the only thing he could think and grabbed the back of the car to hold it. Luckily for all involved Harry wasn’t an average child or person as even an adult would be powerless to stop a car bare handed. Instead Harry desperately dug his feet in and his panicked state of mind would have any wizarding parent on the lookout for a bout of accidental magic. The magic in Harry wildly flared, but before it could escape his body and effect anything in the outside world it triggered the city shaking might that many villains in Japan feared even if they didn’t know its name, One for All. With a metaphysical lurch the galaxy shaped crystallizations of power that was One for All began their intricate dance once more. Harry himself was rather worried. Something bad was about to happen and he would be powerless to stop it. Worrying about his own safety never even occurred to Harry, nor did it occur that a preschooler should not be involving themselves in a kidnapping. Instead Harry felt an electrical sensation all throughout his body. Harry grit his teeth as the car tried to pull away yet didn’t budge. There was smoke pouring from the tires as they spun uselessly while Harry’s feet dug into the ground and he reaffirmed his grip on the car. The two men up front began panicking and they wheels futilely spun faster. Harry did not let go. Not when the smoke from the tire surrounded him and left him coughing. Not when the tires burst with all mighty bangs. Nor when a police car rapidly pulled up and in front of the getaway vehicle. In fact after the incident was over (turns out a divorced father was trying to kidnap his son) Harry was still there holding onto a now unmoving vehicle. One of the other responding officers noticed him first.

“Kid you alright?” he asked as he approached what he assumed to be a 12 year old. Harry snapped out of his trance and responded.

“Is everyone okay?”

“Perfectly alright, what are you doing here? Geez kid did you try to hold the car back!?” The officer exclaimed. Harry nodded sheepishly.

“Well everything is okay now so why don’t you come over with me and tell me everything that happened.” As the officer led Harry away the hand sized dents in the car went unnoticed, as did the cracks in the asphalt where Harry’s feet had been positioned. The incident would later be attributed to a mechanical failing in the car and Harry would be left with a warning to let professional’s handle the crimes.

 

In his cupboard,  Harry gripped his hand as he felt the power of All for One course through him. Why did he still have his quirk in this world without them? And why did he have access to it again even though he had passed it on to Young Midoriya long ago? While he did not miss the ever present threat of a villain attack he could not help but selfishly feel this new world was incredibly dull without the spark that quirks introduced into society. He frowned as the sparks from One for All petered out. His control was nowhere near what it was in his previous life, and he couldn’t help but sympathize with Young Midoriya a bit. There was something different to One for All in this new life. It felt more ephemeral, harder to grasp, luckily when he could get the quirk to work he was still as proficient in channeling it as ever. Without Recovery Girl here to patch him up he could only imagine the trouble he would be in if he went around destroying his limbs everytime he tried to help someone. Either way he would keep training because you never knew when you would need a hero.

**Author's Note:**

> First teaser chapter to a larger work. Will not take itself seriously.


End file.
